﻿Energy 
  of 
  the 
  Ions 
  emitted 
  hy 
  Hot 
  Bodies. 
  693 
  

  

  fig. 
  3 
  is 
  that 
  the 
  agreement 
  between 
  the 
  observed 
  results 
  and 
  

   those 
  predicted 
  theoretically 
  * 
  is 
  a 
  satisfactory 
  one. 
  We 
  may 
  

   therefore 
  infer 
  that 
  the 
  electrons 
  emitted 
  by 
  hot 
  platinum 
  

   have 
  the 
  distribution 
  of 
  velocity 
  required 
  by 
  Maxwell's 
  law 
  

   to 
  a 
  very 
  considerable 
  degree 
  of 
  accuracy. 
  

  

  It 
  has 
  already 
  been 
  stated 
  that 
  similar 
  results 
  were 
  obtained 
  

   after 
  the 
  slit 
  had 
  been 
  cut 
  in 
  the 
  plate 
  A 
  and 
  the 
  strip 
  arranged 
  

   so 
  that 
  it 
  was 
  a 
  little 
  behind 
  but 
  almost 
  flush 
  with 
  the 
  surface 
  

   of 
  A. 
  Under 
  these 
  circumstances 
  the 
  value 
  of 
  z, 
  the 
  distance 
  

   between 
  the 
  strip 
  and 
  the 
  plates, 
  was 
  increased 
  to 
  O'O 
  cm. 
  The 
  

   mean 
  of 
  tw^o 
  series 
  of 
  observations 
  taken 
  with 
  the 
  heating 
  

   current 
  in 
  opposite 
  directions 
  at 
  an 
  average 
  temperature 
  

   of 
  very 
  nearly 
  1100° 
  C. 
  (measured 
  as 
  1102° 
  C.) 
  gave 
  the 
  

   following 
  values 
  of 
  the 
  ratio 
  of 
  the 
  charge 
  passing 
  through 
  

   the 
  slit 
  to 
  the 
  total 
  at 
  the 
  distances, 
  expressed 
  in 
  turns 
  of 
  the 
  

  

  n-ew, 
  stated 
  : 
  — 
  

  

  

  

  

  

  

  

  

  Distance 
  

  

  

  

  5 
  

  

  10 
  

  

  13 
  

  

  15 
  

  

  17 
  

  

  IS 
  

  

  Observed 
  Eatio 
  . 
  . 
  

  

  . 
  -12 
  

  

  •17 
  

  

  •25 
  

  

  55 
  

  

  •88 
  

  

  1-16 
  

  

  1-35 
  

  

  Calculated 
  Ratio 
  ... 
  

  

  •07 
  

  

  •155 
  

  

  ■34 
  

  

  ■Gl 
  

  

  •90 
  

  

  123 
  

  

  1-44 
  

  

  Distance 
  

  

  19 
  

  

  20 
  

  

  21 
  

  

  22 
  

  

  23 
  

  

  24 
  

  

  40 
  

  

  Observed 
  Ratio 
  . 
  . 
  . 
  

  

  l-o9 
  

  

  1-6S 
  

  

  1-68 
  

  

  i-m 
  

  

  1-38 
  

  

  1-03 
  

  

  •03 
  

  

  Calculated 
  Ratio... 
  

  

  1-58 
  

  

  1-64 
  

  

  r64 
  

  

  1-56 
  

  

  1^40 
  

  

  1-22 
  

  

  •09 
  

  

  It 
  will 
  be 
  seen 
  that 
  the 
  results 
  exhibit 
  a 
  satisfactory 
  

   agreement 
  with 
  the 
  new 
  calculated 
  values 
  corresponding 
  to 
  

   ^ 
  = 
  0'5 
  cm. 
  The 
  pressure 
  recorded 
  in 
  these 
  experiments 
  only 
  

   varied 
  between 
  '0021 
  and 
  '0027 
  mm. 
  

  

  If 
  we 
  refer 
  to 
  the 
  previous 
  paper 
  we 
  see 
  that 
  formula 
  (13) 
  

   [loc. 
  cit.) 
  may 
  be 
  written 
  

  

  Io/»i=| 
  (2) 
  

  

  In 
  this 
  formulae 
  is 
  the 
  distance 
  of 
  the 
  strip 
  from 
  the 
  plates, 
  

   ^ 
  is 
  the 
  width 
  of 
  the 
  slit 
  in 
  the 
  latter, 
  and 
  n^ 
  is 
  the 
  total 
  

   current 
  received 
  by 
  the 
  plates 
  and 
  slit. 
  If 
  the 
  slit 
  extended 
  

   the 
  whole 
  way 
  across 
  the 
  plates 
  and 
  the 
  box 
  behind 
  were 
  set 
  

   so 
  as 
  to 
  catch 
  every 
  ion 
  which 
  passed 
  through 
  the 
  latter, 
  then 
  

   Iq 
  would 
  be 
  the 
  current 
  through 
  the 
  slit. 
  In 
  the 
  present 
  

   experiments 
  the 
  width 
  of 
  the 
  plates 
  was 
  '854 
  cm. 
  and 
  that 
  of 
  

   the 
  box 
  only 
  '60 
  cm. 
  This 
  would 
  indicate 
  that 
  the 
  experi- 
  

   mental 
  values 
  of 
  lo 
  ought 
  to 
  be 
  multiplied 
  by 
  •854/-6 
  before 
  

   being 
  substituted 
  in 
  the 
  above 
  formula. 
  The 
  correction 
  will, 
  

   however, 
  be 
  somewhat 
  less 
  than 
  this, 
  as 
  some 
  of 
  the 
  ions 
  

   which 
  passed 
  through 
  the 
  slit 
  beyond 
  the 
  outer 
  edge 
  of 
  the 
  

  

  * 
  Phil. 
  Mag. 
  [6] 
  vol. 
  xvi. 
  p. 
  909 
  (1908). 
  

  

  